3. In plugin dependencies of XX I added plugis A..Z, so that in the aspects the classes are known.
4. I didn't add plugin XX in dependencies of A..Z, because that would result in a cycle.
5. I added project XX in to AspectPath of A..Z.
That's all that I did. You suggest, that I might have an error in aspect code. I don't think it's likely, because the same aspect copied into one of the projects A..Z works just fine.
What else should I do to make it work?